Inkjet recording ink and inkjet recording device using the same

Abstract

An inkjet recording ink, which contains: carbon black; a surfactant; water; a water-soluble organic solvent; and particles formed of an anionic self-emulsifying poly(ether urethane) resin, wherein the carbon black contains first carbon black whose surface has been treated with an anionic surfactant and second carbon black which has been coated with a resinous polymer, where a mass ratio of the first carbon black to the second carbon black is 10 / 90 to 90 / 10, and wherein the anionic surfactant is a naphthalenesulfonic acid-formaldehyde condensate.

Description

TECHNICAL FIELD[0001]The present invention relates to an inkjet recording ink and inkjet recording device, which provide images of high image density, have excellent jetting stability, and excellent storage stability of the ink.BACKGROUND ART[0002]Compared to other printing methods, the inkjet recording method offers ease of full-color printing since it involves a simpler process. And also, the inkjet recording method has the benefit of enabling the production of high-resolution images despite being of simple constitution.[0003]As inkjet recording inks, dye-based inks are used in which various types of water-soluble dyes are dissolved in water or a mixture of water and an organic solvent. Such dye-based inks have a disadvantage of having poor light resistance, though they are excellent in color tone sharpness. Meanwhile, pigment-based inks in which carbon black and various types of organic pigments are dispersed are superior in light resistance compared to dye-based inks, and thus s...

AI Technical Summary

Benefits of technology

[0063]The present invention solves the aforementioned various problems in the art, and provides an inkjet recording ink and an inkjet recording device, which provide images of high image density, and have excellent jetting stability and fluid stability of the ink.

Problems solved by technology

Such dye-based inks have a disadvantage of having poor light resistance, though they are excellent in color tone sharpness.

However, pigment-based inks are more likely to cause nozzle clogging compared to dye-based inks.

Water-based pigment inks usually contain a surfactant and a water-soluble resin to disperse a hydrophobic pigment therein, but the reliability of images obtained using such inks is extremely low.

However, it is difficult to keep a plurality of components in a state of being finely and stably dispersed throughout the ink for a long period of time.

And so, when a dispersant such as a surfactant is used in a large amount in order to stably disperse such fine particles, a problem inconveniently occurs.

Specifically, the problem, for example, is that air bubbles may be generated inside the ink tank and / or inkjet head, which could cause degradation in image quality.

However, while a given component may be stable when used alone, combined use of several different components has problematically caused degradation of dispersion stability as well as degradation of storage stability.

Although the conventional ink liquids have succeeded to provide high image density with a color pigment ink, a black pigment ink has not achieved to provide sufficient image density and satisfactory black pigment inks have not been provided in this regard.

PTLs 24 to 26 disclose proposes an example in which beads each having a diameter of approximately 0.05 mm to approximately 1.0 mm are used for bead mill dispersion, but a dispersion stability of a resulting dispersion is not sufficient.

However, a resulting ink liquid does not have sufficient dispersion stability, and there are problems such that the ink liquid loses its dispersion stability in the case where a pigment that is not resistant to impacts caused during dispersion is used, and as a result the ink liquid has poor jetting stability.

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